It might take a while before it adopted as a mainstream format, but it looks like steps to standardize the Ultra HD TV broadcasting formats are well underway. The International Telecommunication Union (ITU) recently laid down the technicalities to the next two generations of eye-popping high-resolution TV standards, also known as UHDTV (Ultra High-Definition Television). More specifically, the ITU has classified 4K and 8K as multiples of the existing 1920 by 1080p Full-HD format as defined by the ITU-R Rec. 709 standard.
For instance, 4K has twice the horizontal resolution and four times the spatial resolution of Full-HD in a progressive format. That's 3840 pixels wide and 2160 pixels high in effect. The larger 8K resolution, doubles 4K with a display estate of 7680 by 4320 pixels or 16 times the resolution of Full-HD. Supported frame rates include 24, 50, and 60 frames per second, although the ITU has added support for the optional 120fps as well to portray motion sequences without judder artifacts on displays touting these super high-resolution formats. However, broadcasters will have to make concessions for the increased bandwidth requirements. For instance, an 8K TV programme broadcast at 120fps would demand 320 times the bit-rate of existing HD transmissions.
Although UHDTV will require a couple more years before it's adopted as a general standard, the 4K standard has already been in place for digital cinematography and computer graphics. According to Broadcast Engineering's report, YouTube is the only video hosting service to support 4K at this point in time with its concession for the uploading of 4096 by 3072 pixels (12.6 megapixels) videos.
Source: Broadcast Engineering